1. Field of Invention
This invention relates generally to bop bags which rest on the ground and are normally erect whereby when the bag is punched by a player it then swings away from a vertical axis to a degree that depends on the force of the punch, and then swings back to resume its erect position, and more particularly to a bop bag of this type formed by a fabric casing occupied by an inflated balloon.
2. Status of Prior Art
A punching bag is a stuffed or inflated leather bag that is suspended above ground so that it can be punched by the fists for exercise or training. Thus professional boxers make use of punching bags when training for a fight.
A bop bag which rests on the ground and is punched by the fists serves a function in which exercise may play a secondary role. A conventional bop bag consists of an inflatable plastic pouch formed of polyvinyl or polyethylene material of high strength, shaped to have the appearance of a humanoid figure whose head is at the upper end of the bag.
Confined within the base of the plastic bag is a convex dish that is weighted by sand or other relatively heavy material which is uniformly distributed. When this dish rests on a horizontal ground surface, its center axis which extends through the pole of the convex surface is then aligned with a vertical axis at right angles to the ground surface.
The center of gravity in a convex dish is at its center pole, for this is the fixed point in the dish through which the resultant gravitational attraction acts. When therefore one punches the bag to cause the convex dish confined in its base to swing away from the vertical axis to a degree that depends on the force of the punch, the gravitational force acting on the dish will cause it to swing back and return the bag to its erect position.
In a suspended punching bag, a punch causes the bag to swing upwardly, and gravity then causes the bag to swing down. But in a bop bag, it is the force of gravity acting on the weighted dish that restores the bag to its erect position.
The popularity of a bop bag cannot to any great extent be attributed to its function as an exerciser, for it has a more significant symbolic function. The bag, being in a humanoid form, serves to symbolize in the mind of the player an individual the player has a strong urge to beat up, but cannot do so directly. In beating up the individual symbolized by the bop bag, the player is then relieved of psychological tensions and stresses.
Thus a player who is a student and believes he is being persecuted by one of his teachers, would be ill advised to physically attack this teacher or any other individual in authority. Similarly, a player who is an employee would be ill advised to attack his employer, however offensive he may find his employer's conduct toward him.
Because of the player's inability to retaliate against an individual whom he finds hateful, and his need to bottle up his feelings, the player is then likely to experience psychological stresses and even depression, and this state of mind may be injurious to the player's well being.
Punching a bop bag which symbolically represents an individual responsible for his psychological state, makes it possible for the player to effectively beat up this individual and in the process of doing so relieve the player of his psychological tension. Hence a bop bag has a usefulness that goes beyond its value as an exerciser.
Conventional inflatable bop bags are formed of synthetic plastic material which must be hermetically sealed, yet be capable of withstanding strong punches. If in order to provide a light weight bop bag use is made of a relatively thin plastic material, this bag, may be ruptured and deflated by strong punches and cease to be effective.
But if a thicker plastic skin is used to make the bop bag, the bag will then be relatively top heavy, and when a strong punch is delivered to the bag it may then swing to a degree where instead of swinging back, the top heavy bag will fall to the ground and not recover its erect posture.
Also with an inflated bop bag having a plastic skin which is blown up by its user, the internal pressure in the bag is relatively low, hence the bag lacks good bounce characteristics. The higher the internal bag pressure, the greater is its reaction to a punch, and the lower the pressure, the more the bag absorbs this punch.
Inasmuch as a bop bag in accordance with the invention makes use of a fabric bag which is occupied by an inflated balloon, of prior art interest is the U.S. Pat. No. 4,384,382 to Spector which discloses a pneumatic playball that has the configuration and appearance of a standard pneumatic athletic ball, such as a regulation basketball.
The Spector ball is constituted by an inner inflatable balloon confined within a fabric outer casing. The outer casing is formed by contoured segments of high strength, non-stretchable fabric material stitched together to create, when the casing is fully expanded, a play ball of the desired shape and size, such as a football or soccer ball. The balloon is a conventional thin-skin rubber balloon whose stem initially projects through a slit in the fabric casing. After inlating the balloon with air so that it conforms to the casing, the stem is then tied into a knot to seal the balloon, and the tied stem is pushed into the casing under the slit. An unconfined rubber balloon has little strength and is easily burst. But when the same balloon is inflated within the confines of a non-stretchable fabric casing, even though the balloon, per se, is inherently weak, the casing does not permit any region of the balloon to further expand beyond its existing degree of expansion; hence the balloon will not burst even if the ball is given a hard kick.
The bounce characteristics of a pneumatic ball is a function of its internal air pressure. The reason the Spector ball has high bounce characteristics is that its internal air pressure is much higher than in a conventional beach ball made of a non-stretchable plastic film. A conventional beach ball offers little resistance to expansion until fully inflated, at which point, since the material is non-stretchable, it cannot be further inflated. But with a stretchable rubber balloon, it takes much more air pressure to stretch the from its initial deflated state to its stretched and fully inflated state. As a consequence, the internal air pressure of the balloon in the Spector ball is much higher than in a conventional beach ball and the Spector balloon is much bouncier.